America first developed its taste for “nostalgia” culture — sentimental, rose-colored journeys into the recent past — in the 1970s.

From its first day to its last, that decade was a wretched time for the United States, and so it made sense for people living through it to lose themselves in memories of days not so long gone that seemed simpler, more innocent and less dirty (in every sense of the word).

Now, in the summer of 2014, we’re in the midst of a 1970s revival.

Only instead of the bittersweet sentiment that nostalgia usually invokes, the primary emotion today is a kind of horrified disbelief at the return of the decay and disorder that characterized our nation during its shabbiest decade.

Consider the ongoing tragedy in Ferguson, Mo. These nightly scenes of street rage following the killing of Michael Brown offer an eerie parallel to the anti-enforcement frenzy that followed the shootings of four college students during a Vietnam demonstration at Kent State University in Ohio in 1970.

Just as protests erupted nationwide after Kent State, we’ve seen marches in every major US city. And, as was the case after Kent State, peaceful demonstrators commingled with more subversive agitators looking not to quell tensions but to inflame them.

Indeed, there is reason to believe Ferguson may represent a tipping point, with libertarians and liberals coming together to discredit law-enforcement and incarceration policies.

In New York City, the reaction to the death of Eric Garner indicates that the ending of stop-and-frisk hasn’t calmed or quieted the Sharptons but has whetted their appetite to delegitimize “Broken Windows” policing — the revolutionary approach that ended the three-decade crime wave in New York City and has continued to make the city safer in the two decades since it was instituted.

The 1970s also saw a general turn among the elites against the NYPD, though in that case, the issue wasn’t so much police brutality as small-time corruption.

The department was paralyzed for years by the investigation by and findings of the Knapp Commission, which Mayor John Lindsay empaneled in 1970 to look into allegations by Frank Serpico (later immortalized by Al Pacino in the film named for him) that his fellow cops were both demanding and accepting graft from local businessmen and drug dealers.

Just as no one could say the National Guard did the right thing at Kent State, and just as no one could defend the NYPD’s notorious “grass eaters” and “meat eaters,” so it is with the cases of Michael Brown and the apparent chokehold:

Obviously, cops shouldn’t strangle a man as they take him into custody, and just as obviously, there ought to be some way police can immobilize a suspect without killing him.

But when cops use such tactics in potentially threatening circumstances, as the authorities in Ferguson have been doing — like firing tear gas and issuing orders for large groups of people to keep moving or disperse — they’re immediately accused not of showing restraint but of excessive force.

The problem, then and now, is that the criticism of police has moved from the specific to the general — from warranted concern about individual acts of excess by individual officers to the unwarranted notion that these excesses happen by design and are the conscious result of police policy.

This constitutes an ideological assault on policing itself, and it had parlous consequences in the 1970s — giving fearful police departments even more reason to stick cops in cars and work as first responders to crimes already committed (so-called “911 policing”) rather than serving as a strong public presence to deter crime in the first place.

Look, I saw “Guardians of the Galaxy,” and, like you, I really enjoyed the 1970s-laden soundtrack; Blue Swede’s 1974 version of “Hooked on a Feeling” brought me right back to the year of my bar mitzvah. The nostalgia ran riot in me.

But I lived through 1974 in New York City, and I don’t want to live through it again — and trust me, neither do you.